The present invention relates to an integrated circuit device and an electronic instrument.
In the Universal Serial Bus (USB) 2.0 standard, the high speed (HS) transfer mode, the full speed (FS) transfer mode, and the low speed (LS) transfer mode are provided. In the HS mode, the FS mode, and the LS mode, data is transferred at a rate of 480 Mbps, 12 Mbps, and 1.5 Mbps, respectively. As electrical characteristics required for an LS mode transmitter circuit, the USB standard specifies that the rise time and the fall time of an output signal be adjusted within the range of 75 to 300 ns with respect to the load capacitance within the wide range of 50 to 350 pf. The LS mode transmitter circuit is unnecessary for a USB device which supports only the HS and FS modes. On the other hand, the LS mode transmitter circuit must be provided in a USB host or a USB device which supports the LS mode.
As related-art examples which realize the LS mode transmitter circuit, a first related-art example discloses providing a slew rate adjustment capacitance to an output node of a transmitter circuit, and a second related-art example discloses controlling gate control signals for transistors forming a transmitter circuit in a complicated manner in order to conform to the standard (JP-A-2000-49585 and JP-A-2001-196916).
However, the first and second related-art examples do not take data transfer in the USB 2.0 HS mode into consideration. When providing a large slew rate adjustment capacitor to the output node of the transmitter circuit as disclosed in the first related-art example, the circuit scale is increased. Moreover, data transfer in the HS mode becomes difficult. According to the second related-art example, since the control of the gate control signals becomes complicated, the circuit becomes complicated and increased in scale.